The roasting and leaching of complex lead-zinc sulphide ores of Utah

One of the most difficult problems which confronts the metallurgical world is the separation and recovery of the valuable metals in a complex sulphide ore containing lead, iron and zinc. As the ore is mined it is practically worthless and therfore some means of separation is absolutely necessary. Until very recently the only method employed was wet concentration, which serves the purpose fairly well but has its limitations. These are mainly that clean concentrates are not obtainable, as the lead concentrate contains considerable zinc, and the zinc concentrate runs high in iron and lead. These products are sometimes marketable, but the lead smelters will not pay for the zinc in the lead concentrates, and penalize for all zinc over 8%. Likewise, the zinc smelters will not pay for the lead in the zinc concentrates and penalize for the iron.